Is chromium sediment, igneous, or metamorphic rock?

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )

If a solution is considered basic, then a) the hydroxide ion and hydronium ion concentrations are equal. b) the hydroxide ion concentration is less than the hydronium ion concentration. c) the hydronium ion concentration is greater than the hydroxide ion concentration. d) the hydroxide ion concentration is greater than the hydronium ion concentration.

Which factor is likely to impact the possible number of compounds ?